Before mammography became the widely used breast cancer screening tool it is today, ductal carcinoma in situ, or DCIS, was a rare diagnosis. DCIS is a diagnosis given to women who have abnormal cells confined to milk ducts branching through the breast. Some believe more women are receiving this diagnosis incidentally, because they are regularly undergoing screening mammography. A finding that used to account for less than 5% of all newly diagnosed breast cancers now represents 25%.

DCIS has become one of those woolly diagnoses. The name carcinoma certainly sounds like it is cancer and the diagnosis evokes fear in the growing number of women who hear it. Still, some doctors, cancer institutions and breast cancer advocates are at odds about what to do about DCIS. It is a contentious subject because the diagnosis is problematic: It relies on perfections of imaging technology, pathology reports and a diagnostician's opinions.

What's in a Name?

The breast is comprised of lobular tissue that makes milk and ducts that carry milk out to the nipple. DCIS takes hold inside of the milk ducts. The cells that line the ducts sometimes grow to fill the ducts (atypical ductal hyperplasia) or become abnormal DCIS cells. Some argue that DCIS should lose to word "carcinoma" because it behaves more like a precursor, marker or future risk factor for invasive breast cancer. By definition, DCIS is not a life-threatening disease in itself because, as the name says, it stays put (in situ is Latin for "in the original place"). This is why DCIS is also called stage 0 or non-invasive cancer.

But it could break the boundary of the duct(s), spreading into other parts of the breast and beyond to become invasive or infiltrating breast cancer. It's just that it is hard to know which ones are aggressive enough to breakthrough and which ones will have a low risk of ever becoming invasive. It could also take many years to become invasive.

If you treat DCIS like you would invasive breast cancer, treatment can offer the promise a cure (96%–98% disease-free survival). However, women with DCIS receive the same aggressive treatment reserved for women with invasive cancer as a preventive measure, including – breast-conserving surgery (lumpectomy), breast removal (mastectomy), radiation therapy and hormone therapy (ie, Tamoxifen). Aggressive treatment can subject women to emotional distress and physical impairment. Since DCIS tumors are in the breasts’ ducts, they aren't always confined to one area, which sometimes means a substantial portion of the breast needs to be removed – a total mastectomy or quadrantectomy (partial mastectomy). The after-effects of this type of radical surgery can muddy the view of the breast tissue during follow-up imaging studies.

If you don't treat DCIS as you would cancer, it could conceivably become invasive down the road. This could be life threatening especially if treatment doesn't begin early or if a woman is lost to follow-up or forgoes regular breast imaging surveillance or treatment altogether.

Dodgy Diagnostics

Complicating things even more are the criteria radiologists and pathologists use to distinguish benign breast tumors from DCIS and other early breast cancers may vary by institution or clinician, and is intensely influenced by expertise of the interpreters. Like any other diagnosis, mistakes can be made.

Because DCIS doesn't necessarily cause a lump it is difficult to detect during a clinical breast exam performed by a healthcare professional or with a self-breast exam (80% are diagnosed by mammography alone). DCIS however, takes on a distinct appearance on standard X-ray mammography – lines and clusters of tiny calcium deposits – and has certain subtle characteristics. It takes an experienced radiologist to look at the films to decide if the changes are worrisome or harmless.

When the cells look suspicious on a film, the radiologist makes a recommendation that a sample of tissue be removed using a tiny needle (biopsy). The tissue is fixed across a glass slide to be examined under a microscope by a pathologist who will generate a report on the tumor's structural features.

Types of DCIS cells

Cribform – open spaced gaps between cells

Comedeo – containing a center of dead cells

Papillary – fingerlike

Solid

Combination

The pathologist will classify DCIS as high-, intermediate- or low-grade. Some combinations are considered more aggressive.

No Crystal Ball (Yet)

Ideally, it would be great to have a way to predict if, or when, DCIS will progress to invasive cancer and what factors determine if it will. In a study of women who had DCIS suspected with a core needle biopsy, 15% were found to have invasive cancer after the tumor was removed. But that leaves a lot of uncertainty for the non-invaders.

If the trend for diagnosis continues at its current pace, the National Institutes of Health estimates that in 10 years, more than 1 million US women will be living with a diagnosis of DCIS. Which means a lot more women will be facing hard treatment decisions. The goal, as always, is to select the treatment that not only offers the best overall disease-free survival to prevent cancer from recurring, but also the least toxic option and one that preserves the integrity of the breast and quality of life as much as possible.

With invasive breast cancer doctors consider several factors to guide treatment decisions: family history, disease-free margin measurements, molecular characteristics, tumor grade, number of lymph nodes affected, cell surface receptor status, genetics and tumor size. Right now women with DCIS are typically treated with lumpectomy alone or followed by radiation therapy, which destroys any cancer cells that may have been left behind after surgery. If she also is estrogen-receptor positive, she will receive hormone therapy that disables estrogen production because estrogen fuels the growth of estrogen-positive breast cancers.

Researchers are now looking for biological markers that can predict if a DCIS tumor is at low or high risk for becoming invasive, thereby answering the question about what treatment, or combination of treatment is best. This "molecular profiling" will hopefully provide answers that will help women and their doctors make better decisions about treatment. For instance, one study found the risk for subsequent invasive cancer 8 years after a DCIS diagnosis was highest (20% higher) if the original tumor could be felt during a breast exam vs. found incidentally on mammography, or if she was positive for 3 biomarkers. If these results are replicated, a test for these markers will help guide decisions.

The medical community is also devising more sensitive imaging methods that will hopefully be more precise about detection and size. Ultrasound imaging may be combined with traditional mammography, and digital mammography, which produces a digitized electronic image, and breast MRI, may improve on the visualization of calcifications and tumors. In the future 3D technologies (breast tomosynthesis) may be available.

Being a Smart Patient

Diagnosis of early breast cancer is not only affected by problems in diagnosis, but also because early breast cancer is inherently unpredictable. The best you can do is become a proactive and prepared patient.

Here's Dr. Oz's Advice

Know Your Doctors: Get the name, credentials and contact information of every pathologist, radiologist, oncologist and surgeon involved in your care. Choose the doctors and institutions with the best breast cancer experience.

Be a Record Keeper: Get copies of the all imaging films if possible and transcribed findings from radiologist who performed and assessed your mammogram. Make sure they were compared to previous pictures if you have had a mammogram before. If you have had a biopsy, ask for a copy of the pathology reports.

Ask for Translations: It is likely that a pathology and mammography report will be gibberish to you. Ask your doctor to explain each word to you in plain language.

Demand Experience: If you have had a biopsy, make sure the pathologist who is assessing the slides is an experienced board-certified pathologist from an accredited institution. Send the slides to get a second opinion especially if surgery is recommended. Ideally, the pathologist should be reading a least 200 breast cancer slides a year to be able to detect the subtleties between benign and early breast cancer cells.

Become a Fact Finder: Learn your cancer's receptor status, biomarker profile, tumor grade, margin measurements and tumor size. This will be used to guide treatment recommendations and follow-up care.

Keep a Close Watch: Perform monthly breast self-exams to familiarize yourself with the terrain. This way you will know when something is new. And keep to a prescribed schedule of regular mammograms, typically every 1-2 years beginning at age 50, or sooner (age 40) if you have certain risk factors such as a family history for breast cancer. The intervals between mammograms will depend on risk factors and/or prior findings such as DCIS. Click here for Dr. Oz’s breast self-exam guide.